1. Field of the Invention
The present invention relates to a stacked structure of semiconductor chips, a memory card, and a method of manufacturing the stacked structure of semiconductor chips.
2. Related art of the Invention
In recent years, small memory cards such as an SD memory card are often used as recording media in cellular phones, digital cameras, and the like. According to improvement of functions of apparatuses such as an increase in the number of pixels of the digital cameras, an increase in capacities of the memory cards is demanded.
A stacked structure formed by stacking plural semiconductor chips in order to realize such an increase in a capacity of a memory card is disclosed. FIG. 26 is a diagram showing a stacked structure of semiconductor chips of the prior art. In the stacked structure of semiconductor chips shown in FIG. 26, a semiconductor chip 105 is mounted on one side of a substrate 107. Four pairs of the substrate 107 and the semiconductor chip 105 are stacked on a mother board 104. The substrates 107 arranged to be adjacent to each other in a vertical direction in the figure are electrically connected by solder balls 108. In the figure, the substrate 107 arranged at the bottom and the mother board 104 are also electrically connected by the solder balls 108.
As shown in FIG. 27, a stacked structure in which semiconductor chips are arranged on both sides of the substrates 107 is disclosed (see, for example, Japanese Patent Laid-Open No. 2002-207986). In the stacked structure of semiconductor chips shown in FIG. 27, two pairs of the substrate 107 and the semiconductor chip 105 mounted on both sides of the substrate 107 are stacked on the mother board 104. In places where the semiconductor chips 105 are opposed to each other, insulating sheets 125 are arranged.
However, even if it is attempted to realize a further increase in a capacity of the SD memory card, a size of the SD memory card is determined according to its own standard and it is necessary to secure to have a certain thickness of the substrates 107. Therefore, there is a limit in stacking the semiconductor chips 105 by the method described above.
In order to realize the increase in a capacity of the SD memory card, it is also conceivable to use a semiconductor chip with a large capacity. However, compared with the structure formed by stacking plural semiconductor chips with low unit cost and a small capacity, cost substantially increases.
The present invention has been devised in view of the problems of the stacked structures of semiconductor chips in the past and it is an object of the present invention to provide a stacked structure of semiconductor chips in which semiconductor chips larger in number than in the prior art can be stacked, a memory card, and a method of manufacturing the stacked structure of semiconductor chips.